Improvement in spring-headed screw-bolt



tlnitml eC-@inist @aient @Wina Letters Patent No. 99,473, dated .February 1, 1870.

IMPROVEMENT IN SPRING-BEADED SCREW-BOLT.

The Schedule referred to in these Letters Patent and making part of the same.

To all whom it may concern Be it known that L'DANIEL R. PRATT, of the city, county, and State of N ew York, have invented a newr and useful Improvement in Screw-Bolts, and which I denominate as Pratts Spring-Headed Screw-Bolt; andI do hereby declare the following to be a full, clear, and exact description of the construction and operation of the same, reference beinghad to the annexed drawings, making a part of this specification.

The nature of my'invention consistsin the application to the head of a bolt, of, ordinary construction, a metallic cap, the top of which is open, and conformi'ng, as near as may be, to the size andrshape of the Ihead of the bolt, a hole, the size of the shank of the bolt, being made in the bottom part of the cap, .through which thebolt may pass, and placing within said cap Indiarubber, coiled, or cnp-shapedsprings, before placing the bolt in the same, so that the lips' formed upon the upper .side 'of the cap, being bent over and upon the head of the bolt, the Whole will form my springheaded bolt.

In thedrawings- Figure 1I represents a perspective view of the cap 'and bolt, with the lips a a. turned up.

Figure 2, a similar View, with lips a a bent down upon the head of the bolt, securely fastening the cap to the bolt.

Figure 3 represents a cross-section of the cap A.

B is the bolt.

B', the head of the bolt.

1 represents a rubber spring; and

a a, the ears of the cap. l f

. Figure 4 shows, also, a cross-section of the cap, con- .taining Within it different styles of springs.

By this form of construction, I yam enabled to'adjust the head of the bolt evenly to any surface, being a plane, or approximating thereto evenly, .and prevent an undue strain upon any particular point o1' portionof the bolt-head, whereas, without'this arrangement the heads of bolts are liable to derangemcnt and fracture.

It is also more important to thus protect the head of the bolts than it isV thescrew-nut C, for the latter can be readily replaced, while the former, if injured orbroken, causes the loss of the wholebplt, or its rel pair is attended with very considerable expense.

The nnt C can-be fastened or prevented from turning by any well-known device, and the yielding nature of the springs, at the bolthead, will tend to prevent jarring and dislocation oi' the bolt.

What I claim as my invention, and desire to secure by Letters Patent, is-

1. The construction and arrangement of the cap A, containing within it the springs 1, 2, 3, or either of them, whencombined with the bolt B and its head B', in the manner and for the purpose herein described.

2. rlhe within-described method and `means 0f attachment and seeming the springs and bolt within the cap, in the manner and-for the purposes herein set forth. i

DANIEL R. PRATT.

Witnesses:

B. F. JAMES, EDM. F. BROWN. 

